title: The effect of extending mild hypothermia on focal cerebral ischemia and reperfusion in the rat.
abstract: The aim of the present study is to compare the influence of timing and duration of mild hypothermia on rats subjected to 3 h of middle cerebral artery occlusion followed by 72 h of reperfusion. Sixty-four Sprague-Dawley rats were divided into three mild hypothermic groups according to the duration of mild hypothermia (MHT 32 +/- 0.2 degrees C): intra-ischemia (MHTi); intra-reperfusion (MHTr); and intra-ischemia/ reperfusion (MHTi + r). Our control group was normothermic (NT 37 +/- 0.2 degrees C). Reversible focal cerebral ischemia was carried out in rats with a suture technique. Cerebral blood flow was measured by laser Doppler flowmetry to confirm occlusion and reperfusion. The permeability of the blood-brain barrier was determined by the extravasation of Evans's blue dye, and infarct volumes were measured by 2,3,5-triphenyltetrazolium chloride staining at 72 h after reperfusion. Acute post-ischemic hyperperfusion and delayed hypoperfusion in the ischemic perifocal area and sustained hypoperfusion in the ischemic core were inhibited in MHTi + r and MHTi rats (p < 0.05) as compared to the NT rats. The action of MHTi + r on preventing post-ischemic progressive hypoperfusion in the perifocal area was more effective than that of MHTi 2 h after reperfusion (p < 0.05). Blood-brain barrier disruption in the basal ganglia and cortex areas was significantly reduced in both MHTi + r and MHTi groups, and especially the former. Infarct volume was significantly reduced in both MHTi and MHTi + r groups (p < 0.05). MHTi and MHTi + r have protective effects for reducing ischemia/reperfusion injury. The potential mechanisms may include inhibition of post-ischemic hyperperfusion, and delayed and sustained hypoperfusion.
authors.affiliation: Department of Neurosurgery, Hua Shan Hospital, Shanghai Medical University, Shanghai, China.
authors.forename: F P
authors.initials: FP
authors.lastname: Huang
authors.forename: L F
authors.initials: LF
authors.lastname: Zhou
authors.forename: G Y
authors.initials: GY
authors.lastname: Yang
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000628:therapy; D001812:Blood-Brain Barrier; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D005070:Evans Blue / Q000493:pharmacokinetics*; D007036:Hypothermia, Induced; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging / Q000628:therapy*; D017078:Laser-Doppler Flowmetry; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000000981:diagnostic imaging / Q000628:therapy*; D014463:Ultrasonography
chemical_list: D005070:Evans Blue